Replaces jQuery._Deferred with the much more flexible (and public) jQuery.Callbacks. Hopefully, jQuery.Callbacks can be used as a base for all callback lists needs in jQuery. Also adds progress callbacks to Deferreds (handled in jQuery.when too). Needs more unit tests.

Construct boolHook and rboolean regex to deal with boolean attributes. Fixes #9129. Fixes #9123.
- Construct regex for all attributes which are boolean attributes by specification.
+ This allows us to do what users expect with enumerated attributes and allows us to no longer complicate the issue.
+ People are just too confused with passing "true" instead of true when they should, so we won't have to worry about that anymore.
- Modularize code for dealing with boolean attributes into a separate hook to keep attr short and fast.